Study Of Their Application On Surface Film Of Carboxylic Acids, Acylamides And Esters For Oil-collecting Agents On Water Surface

Four kinds of carboxylic acids which are lauric acid, myristic acid, palmitic acid and stearic acid, four kinds of sorbitan monocarboxylic esters which are span-20, span-40, span-60 and span-80, and five kinds of N,N-dialkylacylamides which are N,N-dimethylstearamide, N,N-dimethylpalmitamide, N,N-dimethyhnyristamide, N,N-diethylstearamide and N,N-diethylpahnitamide were selected as active constituents. Several kinds of fatty alcohols, carboxylic acids and esters such as hexanol, hexylic acid, heptylic acid, octanol, decyl alcohol, butyl acetate and isoamyl acetate were selected as solvents. The isotherms of the active constituents and their solutions in the above-mentioned solvents were determined with film balance at 27 , and their interfacial tension were determined with interfacial tension instrument at 24~28 , with which the characteristic of these active constituents' film and their properties in the application of oil-collecting agents were studied. It is shown that lauric acid is not suitable for oil collecting agents because its film pressure is not big enough. A section with higher film pressure of 40mN/m was found at the isotherm of myristic acid after myristic acid was modified with some solvents. Sections with higher film pressure of 40 mN/m were both found at the isotherms of palmitic acid and stearic acid, and a section with a stable film pressure, which is 50 mN/m, was found at the isotherm of stearic acid after it was modified with solvents. Myristic acid, palmitic acid and stearic acid are all be used in oil-collecting agents, and their capability for collecting oil under the decreases in the order of same conditions is stearic acid, palmitic acid and myristic acid. In the five kinds N,N-dialkylacylamides, it is difficult for N,N-diethylacylamides to perform effectively in oil collecting because the maximum of film pressure caused by N,N-dialkylacylamides is just about 38 mN/m. Their capability for collecting oil under the same conditions decreases in the order of N,N-dimethylstearamide, N,N-dimethylpahnitamide and N,N-dimethylmyristamide. Sections with higher film pressure were all found at the isotherms of span-20, span-40, span-60 and span-80, and the data is between 35~45mN/m for span-20 and span-80, and about 70 mN/m for span-40 and span-60. Solvents affect span-20 and span-80 slightly, but heighten the film pressure of span-40 and span-60 from less than 22 mN/m to more than 40 mN/m while they are operating, and lead them to operate in form of monolayer film while improving their properties.Oil-collecting experiment shown that the persistence of the carboxylic acids as active constituents is excellent, but their ability to respread is poor. If solvents are used to modify their ability to collect oil, the result of such solvents as fatty alcohols and carboxylic acids with seven carbon atoms in their carbochain is best, and the solvents can lead stearic acid to keep such compressing rate to oil slick as higher than 70% for more than 72 hours. The other fatty alcohols, carboxylic acids and esters improve very little or even weaken the persistence of carboxylic acid active constituents for collecting oil. The persistence of N,N-dialkylacylamides for collecting oil is poor, and the oil film spread completely in 24 hours, when they are used without any solvent. Hexanol and heptanol with less carbon atom in their carbochain weaken the persistence of N,N-dimethylstearamide and N,N-dimethylpahnitamide for collecting oil. However, octanol and decyl alcohol with more carbon atoms heighten it generally. Decyl alcohol and sec-octanol enhance the durance of the two kinds of N,N-dialkylacylamides to more than 48 hours even 72 hours. Hexylic acid, butyl acetate and isoamyl acetate can also enhance the persistence for collecting oil remarkably. Solvents affect the persistence of sorbitan monocarboxylic esters for collecting oil obviously. The persistence of Span-20 and Span-80 is weakened when the solvent is hexanol or heptanol, and it declines with the decrease of carbon atoms when the solven...